Field of the Invention
The present disclosure relates to a liquid discharge head that discharges liquid, a liquid discharge device on which the liquid discharge head is mounted, and a method for manufacturing the liquid discharge head.
Description of the Related Art
A liquid discharge substrate includes a silicon base and has an element substrate and a discharge port member for discharging liquid. The element substrate includes a pressure generation element that generates pressure for discharging the liquid such as ink. The member is provided on a surface side of the element substrate. The liquid discharge head includes the liquid discharge substrate, a wiring substrate including wiring that is electrically connected to the liquid discharge substrate, and a support substrate on which the liquid discharge substrate is joined. The wiring substrate is a member for supplying power to the liquid discharge substrate and the liquid discharge device main body, and is electrically connected to the liquid discharge substrate and the liquid discharge device main body.
Generally, the liquid discharge substrate and the wiring substrate are electrically connected to each other through wire joining or with a flying lead. After the electrical connection has been established, a liquid sealing agent is applied to an electric connection portion between the liquid discharge substrate and the wiring substrate, which includes a wire and lead, and then is cured. Thus, the electric connection portion is sealed with the sealing agent electrically insulated and protected from liquid. The liquid sealing agent used in this case includes an epoxy resin or acrylic resin composition of thermosetting, ultra violet (UV) curing, or moisture curing type.
In a case of one known method for protecting the electric connection portion with the sealing agent, a sealing agent with a low viscosity and a sealing agent with a high viscosity are respectively applied to an upper and lower side of the wire or the lead, and both agents are cured. With the sealing agents of two kinds of viscosities, the sealing agent can be evenly applied to the lower side of the wire or the flying lead.
However, if the sealing agent with a low viscosity is applied to the lower side of the electric connection portion, the agent may spread beyond the lower side of the electric connection portion. If the sealing agent of low viscosity spreads beyond the electric connection portion, an amount of the sealing agent sufficient for protection of the electric connection portion does not stay at the lower side of the electric connection portion. Thus, the electric connection portion cannot be effectively protected.
Japanese Patent Application Laid-Open No. 2011-240549 discusses a configuration for addressing this problem. More specifically, the liquid discharge substrate is disposed in an inner side of a device hole formed on the wiring substrate. A sealing agent is applied to a groove defined by the liquid discharge substrate, the support substrate, and the device hole. Thus, the agent sealing the electric connection portion is stemmed in the device hole, and thus can be applied to the lower side of the electric connection portion without spreading beyond the electric connection portion.
However, the wiring substrate provided with the device hole surrounding the liquid discharge substrate becomes larger than that without the device hole, and thus a size of the liquid discharge head also becomes larger. This issue arises in the liquid discharge head, such as a line head, with a plurality of liquid discharge substrates arranged in an arrayed direction of discharge ports. More specifically, if each liquid discharge substrate is surrounded by a device hole, the wire substrate and the liquid discharge head become all the more large.
On the other hand, without walls for enclosing the sealing agent provided around the liquid discharge substrate, the sealing agent flows beyond the electric connection portion and thus fails to stay at a desired position. Thus, the electric connection portion is difficult to effectively protect. Especially, a sealing agent with a low viscosity is likely to spread outside the desired portion.